FIG. 1 schematically illustrates a prior art Digital Subscriber Line Access Multiplexer (DSLAM) 10 used to provide high-speed Internet (and optionally telephone service) access to service subscribers 12 in a manner well known in the art. The DSLAM 10 includes a plurality of line cards 14. Each line card 14 is provisioned with a plurality of DSL ports 16, typically 24 or 48 DSL ports 16. Each subscriber 12 is connected to one of the DSL ports 16 by a subscriber line 18 via a DSL modem 19, also in a manner well known in the art. The line cards 14 are further provisioned with interworking functions 22, which perform interworking feature processing 24. The line cards 14 are connected to a Local Area Network (LAN) switch 26, which is in turn directly or indirectly connected to a service provider network 28. The communications path 30 to the administrative workstation 20 may include multiple service provider networks (e.g. Service Provider A 28, Service Provider B 29, and Service Provider C 31).
As understood by those skilled in the art, subscriber services provided to the subscriber 12 by the DSLAM 10 must be provisioned using an administrative workstation 20, which is typically not connected directly to the DSLAM 10. Service provisioning can be complex and frequently requires verification or troubleshooting. Traffic flows bidirectionally between the subscriber 12 and the service provider 28 via a communications path 30. Provisioned interworking features are processed by interworking feature processing 24. If an error is made during service provisioning, service to the subscriber 12 may be denied, or the service provided may not accord with their service subscription.
In order to verify service provisioning, test heads 32 have been invented. The test head 32 is designed to be connected to a test bus interface on the line cards 14 of the DSLAM 10, as schematically shown. Any DSL port 16 can be administratively connected to the test bus (not shown) and thereby to the test head. Although the test heads 32 were originally designed to test only the physical layer of connectivity to the subscriber 12, the functionality of some test heads 32 has been enhanced to permit testing of higher layer functionality via the integration of reference DSL customer premise equipment (CPE), which can verify the service provisioning. However, the capital cost of such test heads can be prohibitive. Furthermore, there is a growing trend toward locating DSLAMs remotely in Fiber to the Neighborhood (FTTN) deployments. These deployments typically support fewer DSL customers thereby further increasing the cost per subscriber of deploying a test head.
In order to reduce operating costs, equipment self-testing for verifying physical layer connections has been invented. An example of this is built-in single-ended line testing (SELT) and dual-ended line testing (DELT) in DSL transceivers. However, Layer 2 and higher provisioning can still only be tested using a specially equipped test head, as explained above.
There therefore exists a need for a method and apparatus for verifying end-to-end service provisioning and functionality throughout a network used to provide DSL services.